Telephone-exchange system



c..w. KECKLER;

TELEPHONE EXCHANGE SYSTEM- APPLICATION FILED AUGJI, 191]- Patented Dee. 13, 1921.

2 SHEETS-SHEET l.

I C. W. KECKLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUGJI, 1917- Patented De0.13,'1921.

2 SHEETS-SHEET 2- H B Pas/W0 37 I A Pas/Tm //1 van fan Char/e5 14 Keck/e1.

circuits and apparatus to the usual signaling current at the A posi-f tion to connect a source offproper current to the line ofithe subscriber called r r i of the party line signakofthesubscribers exchange is utilized' to mmg eenan, or lxmwnmr; NEW JERSEY, Assreivion ro-wnsrnmvrit'ncra're I 1 company,- INCORPORATED-,"OENEW ORKy-NqYg A CORPORATION or"New160 3 ofNew Jersey, have inye'nted certainj newand useful Incprovern'ents in TelephonerEnchange Systems, of which the following 1s a full,' clear, conciseQaiiid exact description; This invent on relates; "to telephone ex change systems, and "more particularly to or selective party line s'ignaling insuch systems; x The principal object of the inyentioii s current or combinations:thereofv at a would employ in signaling ii 1 1 p fty at the A'eXchange; and withouttlie 0p yond settingaipthedesiredf 'connelction' This object: is accomplished by the proyifl erator'being. required 'to dof;afnything' be sion of means at the B position,,responsive' his particular party' signal. 7

Another object of the invention is to provide, a system wherein usual signaling apparatus necessar'yfor the operat on associated -with thej automatically apply signaling current from this end, means are provided; at the B-eX- change responsiveto the particular signaling current applied "at the 'A exchange which 1 operates to supply signaling?current'troni. apparatus at the B i exchange adapted to actuate the signals allotted to particularsta-f tions of party 'line's associated :with tlie "B erator at" one office can'efict" the selective operation of apparatus at a secondiofliceiby and'in accordance with the parti-cular' de-L sired signaling current 'orf'conibin'ations thereof selected at thefirst' oificeffron a plu' q Specification;0f Letters Patent. 1

e ii nsa of difierentj characteristics.

t e fe' dine, op'erator B is; supposed. to select 7 such line; In: systems using but a, single i wih he th flBflk rre p nne d n e -s l d,t 'irroxee P rt wi h? d er-e f e iw aceeee rsT r ralit if s signaling ar as "different characteristlcs [available] thereat. i111" ac.-

cordance withthislfeature ofthe invention; f limfi lng c rcuit extends between the .two'

with thefpar'ticula desiredsignaling cur- "1 rent selecte'djand applied tosaid -circuit at j :1 3' plurality "of signaling currents f scriber who isf onf a party line associated w th ianotherexchange, In, such acase it} party toobtain .the'fexch desir in; the usual w e-Jim :A

eratorthen-communicatesoverariorder wire," i i circu1t w1 th;, a f l3 operator at the "exchange;

of the" called "party' fandjthe EB operator; on 1 ,7 A

e gi i d th lin an ne yl mberb im subscriber I desired informs: the A operator the particulantrunkL'to befiised ibetween the; v w ex anie'es' adgpla s ike mumsp u of this trunk intovtliefljack 'ofthei lineyofthe 8 upon places the callingf'endflof herlcord "or l called subscriber; The 1 operator-there}:

link circuit, already, associated with the call- I ing--.line, finto the -jack' ofthe.allotted triinkQ the'usualapparatus necessary for the pp: eration of the partyline*signals of su'b f, scribers associatedv with the '3 exchange to,

' signal subscribers of the Bexchange. f'To If the party systen'i be one having an indiival a k, f r-ea h e t e' Peri e e.

the propergroup of jacks. and the particu lar jack therein individual to the desired party' and 1:0 connect fsignaling current to relieved of haying to'f select a p articular .j ack 1 0? 1-.6up allotted to the different parties on "that line; {has heretofore been. under the 1 1 exchange corresponding to the] i'part'y line station associated with the" A exchange whose signal is operatedfby the particular current applied at the A position. If "A further object ofthe invention is to provide a telephone system wherein an ,op-

duty cf lselectingfanfd applying the properfloov V p v p t to-Loperate theQsignaI of i the desiredpa r ty'.*Infboth. systems the re N f spons ibil'ityofvselectingfth'e"proper;party is placed upon the B operfator. ,Thl s whil'e, j the A operator'had comp'ltfiontroloffthe 1105 connection as soon'f as thecal lingf party an.-

'swe'rs she'hadno directwayoffdetermining g p signaling curr e .happ n i h e 'elph iiei wfi scriber vd sires connection with another" sub-f- I ri la i' j gack perpartylinathejB operator, although '-line number of the .desired party and so plicable to party lines having but a single jack per line, the Boperator is given only the handles a party call in the same manner as a private line call. The duty of selecting and signaling the proper party devolves upon the A operator, who is thus in a positlon to directly ascertain if the proper key for the particular party desired was Operated, without the aid of the B operaton The A operator, however, except for obtaining the trunk assignment from the B operator, handles the call in the same manner as if the multiple jack of the called party were directly available. The jackof the trunk assigned would correspond to the jack of the called party, so far as the A operator is concerned, and she would insert the calling end of the cord' therein and operate the proper party key of the ringing key associated with the particular cord to supply signaling current in the same way as if signaling a party line subscriber associated with the A exchange and having his line jack located on the A operators switchboard. The supervisory signals would operate in the same manner and indicate v the same condition of connection,

whether'the call was a trunk or local call, and the connection would be supervised by i the A operator in the same way in both cases. Referring to the drawings, which illustrate embodiments of the invention, Figure 1. is a diagrammatic showing of circuitsand apparatus'for utilizing the invention in connection with a party line telephone system using biased signals; while F 1g. 2 1s a slmilarshowing of the invention as applied to a line system using harmonic slgnals. The invention will behest understood from adescrip-' tionof the operation'ofthe respective sys tems shown in the drawings.

' In Fig. 1, the necessary circuits and apparatus of the invention, as applied to superimposed current signaling systems using biased signals, is indicated; the circuit andapparatus' of the calling subscriber and thatat the A operators position vbeing indicated to the left of the dotted line, and that at the B operators position and at the called line heing indicated to the right thereof.

The party at the calling substation 3 would signal the A operator,'who would insert the answering end of a cord into the jack 4 of the calling party, and connect her operators set (not shown) with the subscriber in the usual manner. The calling subscriber would give the exchange,number and party indicaconnected to another exchange. The A operator would thereupon communicate with the B operator at the desired exchange over an order wire circuit (not shown), and give 7 only the number of the called party. The B operator would test the jack 5 of the called line and if idle would insert the plug 6 of an idle trunk extending from the A operators position into jack 5 and notify'the A operator of the number of the trunk which had been selected. 2 p 7 Upon the B operator plugging into the jack 5 a, circuit is completed through; the usual cut-off relay 7 of the called line to ener- .gize the relay 8 of the trunk at the B operators position; this circuit extending from-- completed to operate a relay 15, which serves.

to temporarily open thecord circuit of the B position, and to prepare for the transmission of signaling current to the called line. This circuit extends from grounded battery, front contact and left-hand armature of relay 8, conductor 16, winding of relay '15,:outer lower armature and back contact of relay 17,

conductor"l8,and back contact and armature of a slow operating relay 19 to ground. The

relay 19 is both slow to pull up and slow to release for reasons. to be hereinafter described.

The A operator would depress the proper party key associated with the cord in use at the'time the calling subscriber gave her the number or while obtaining the trunk assign ment from the B. operator. A circuit is thus preparedandis completed on the A operator placing the plug 20 of her cord in the jack 21 of the assigned trunk to sendysignaling current over the calling end of the cord'to actuate apparatus at the B position. Assume that the party key K, which corresponds to the party indication of the called subscriber, has been operated-to disengage the center from the inner springs and, to engage them with the outer ones. On the A operator placing the plug 20 in the jack 21 ofthe trunk to the B position a circuitis completed to operate relays 22 and 23, this circuit extendmg. from ground, through resistance 24,

sleeve connections of jack 21 and plug 20,

conductor 25, winding of relay 22, conductor open at the upper armature of relay 22. It 1s, therefore, impossible to have signaling.

current on the tip 'ofthe plug 20 duringinsertion thereof and any possibility of giving a false signal through the tip of. the plug contacting with'the sleeve spring of-the jack is thus avoided. I Immediatelyon the A operator plugginginto the jack 21, and the opere ationof relay22, a circuit'is completed to energize the relay 14fat the position this circuit extending irom the" positive side oi j battery 29, tip side of the A cord to the back i contact and upper armature or ren eo and 1 upper armature and front contact'of relay 22, tipjcon'n'ections of theplug and jackf 10; 21', conductor 31,upper left-hand winding 32 of the repeatinglcoilattheB position, conductor 33, both windings of relay 14, 1Q W.er-

' left-hand winding 34 of the repeating coil, conductor '35, ring connections of jack2l 1 5 and plug 20, ringside ofA cord through the lower armature and back contact. of res;

' lay30, and winding of marginal relay 36to' the other side'of battery 29. The .relay 3.6

is so marginedthat'it willnot operate when 20. inseries with both windings ofrelay 1 4, but

will operate when the left-hand windingisx} removed from the circuit, as hereinafter 'ex pla'ined, The operation oftherelay 14opens the circuit of the supervisory signal 10, which is thus extinguished, and indicates to the B operator that the A operator has, con nected with the assigiiied. trunk, 9

ThekeysK" and I operate with the tipside of the linein the arranged. to synchronize with another con stantly rotating interrupting device 40. v The device 40;has'tw o segments connected so as V to impress negat ve; superlmposed I signaling 2 vi0 current on the conductor 41 during apart of the, revolution andto remove thissignaling current and substitute direct current. during the remainder of the revolution, the c011- ductor 41 being connected with-the negative 45 side of the battery 38 under 'this condition,

' The application of battery current to.;t he

conductor 42 extending to the relay 3Z' 'co'incides withthe applicationof signaling cur- I rent to the conductor41, and iii-either ofthe keys 1; or K is depressed, completesa circuit forthe relay 37 at this time. The ,circuit for the;operation;of Key Kfgextendsfi from grounded battery 38, interrupting'device 39, conductor 42, contact 43 in-its normal positiomwinding of relay 37 conductor" 44, contact 45, now, engaged'withthe lower armature of relay ,22, conductor 46, inner.

P, which then returns tojits'nor'mal position.

a and middle right-hand springs of key K"=, inner and middle right-'handsprings oi -key Kflfmiddle and innerright-handsprings of i key K and middle and outer-*right-hand' springs ofiltfv to ground; -Relay 37 onpull-l ing up completes a locking circuit fforitself, extending 'fromgrounded battery 47, lower armatureoffrelay w and contact 43 inathe 1K, to; ground. The operationptf the lower relay iis responsive tofriegative;superims- 2 are arranged to colent over thering side ofthejline. 'iThe cir-i upper armature of relay 37, conductor-1.60,; (front contact andupperarmature-,ofrelay':

Qupperi armature of relay, 1,5,, conductorfii and windingiOf-relayjP to groundh ofl' normal position, and thence over the' jre-l me i m r i n o he ci c it .ifle i u y traced, to theouter 'left-hand-springof key,

armature of relay 37 operates contact 431 to d i n t fr m 1 Hd w 1.142,; e din through thefinterrupting device 39,- to bat ter 3-8.- i -I 'nthe a et aopera ion z h filay 2 completed ai i f u tt o ope ate re ay 30, 7: this circuit iextending .from;,gro und, front contact andlarmatu're oi relay 23, resistance- 8.,. b d 4 ;,e mat ean -back-cont f @Of a slow actuated marginaL-relayJSO, con- Q c l cluctor; 5'1, armature and backcontact of j'rea,

"lay 52,conductor 53, and winding-of relay 30;

t0 grounded battery..;. Theke'y Kf being op-f erated,1energizationof5relay 3O servesto-connect positive superimposed currention the tip side of the cordj and eoinpletes a circuit to operate ai-biased relayPi atithe 13 position;,

the relay Pi; beingresponsive tQ;- .Positivel superimposed-currentandso connected asgtooperateonly @when such current is placed on the tip side ,of the operatofls cord. g -The 9o 5 posed current. over, the tip side .offithe-illine while relays P -and P respond respectively to. positive and negative superimposed cur-:9"

cuit: forthe relaylirextends fromgrounded alternating generator 54-, through battery-55, 1

having skp i e side 1 leading. to afcon-x .stantly rotating inter ting: d i 5 v to 'Jthe i p ing v ;40,,.conductor 57 left-hand winding of relay "50,1 conductor, j

'm ddle-ieithmn springs of a key 1K inner and a middle left-hand springs I ofjiKey Kfi cond'uctor- 5 ,9, front,v contact [and connections, lof-flplug. 20 ,j and jack 21;;con-

ductors 31 and '61-, front iconta'ctlandioute' Relay '1 serves "as: anfaelectromagneti'cIf switching mean to complete a local: operate;

ing circuit fora relay Rfl this.circuit-exi; tending from. grounded :jbattery, front pong, tact and -left-hand-a1mature of relay-8,;con

ductor 63,,armature. and f rontrcontactgiof f Q relayf-Pf, {conductor j64, ;;winding of 'relay;,;- 1R, conductors 65,, and 66,- and-backcon-tact- .1

R" thereupon pulls-.upgdlforniingiaholding 3 and rm u e fre ay' 9,i t0:g f 1l "Relay;

circuit for itself and l-sh-unting out the relay 1! This holding circuit extends from, grounded; battery, frontcontact and; left-hand 3131113,}:

12 5 ;ture of delay 8, conductorsl63 and67,windi flx ring of 1;ela"y$ ,1 2, conductor 69,}; leimhand armature-{front contact and vvinding'jof rej 1 IlayR, conductors 65and?6.6;'and backicon Q,;-.

tact and armatureof relay ajl9, to ground The relays 1 1 and P are associated with relayslt R and B respectively and on operating energize their respective relays R R or R as the case may be, to obtain the proper selection of signaling current at the 'B position to operatethe signal of the particular subscriber desired on the party line with which the plug 6 is connected.

In the meantime, the relay 12, being included in the holding circuit of relay B,

would have pulledup, closing at the outer armature a circuit to shunt out relay 14,

to permit the armature thereof to fall off.

This shunt circuit begins at conductor 31 and extend over conductor 61, front contact and outer upper armature of relay 15, conductor 62, conductor 85, front contact I and outer armature of relay 12, conductors 86 and87, to conductor The armature of relay 14- in falling off, closes a circuit to actuate a relay 88, this circuit ext-ending from grounded battery, armature and back contact of relay lhconductor 13,1nner armatureand front contact of relay 12, winding of relay 88, conductors 89 and 66, andback contact and armature of relay 19, to ground,

' On the operation of relay 88, a shunt path terrupted,

is provided around the relay 12, which is thereby deenergized;-"this shunt path starting at the junction of conductors 63 and 67 and extending over conductor 63 to the inner left-hand armature and front contact of relay 88, and conductor 90 to conductor 69. The relay 88, however, on'pulling up,

completes a holding circuit for itself which is unaffected by'the deen'ergization-of relay 12, this circuit extending from g'roundect battery,fr0nt contact and left-hand armature of relay 8, conductor 63, inner left-hand armature and right-hand armature and Winding of relay 88, conductors 89 and66 to back contact and armature of relay 19 to ground. The shunting out of relay 14 also permitted marginal relay 50 to operate,

thereby openingi the shunt circuit about relay 52, which thereupon pulls up over a cir cuit from ground, front contact and armature of relay 23, resistance 48, conductor 99," winding of relay 52, conductor 53, and

winding of relay 30 to grounded battery.

The energization of relay 52-completes a holding circuit therefor through its arma ture and front contact to grounded battery, and also shunts out the relay 30, whose armatures'thereupon fall off. The circuit .by which signaling current at the A posi tion is supplied to the A cord is thereby in while the connecting circuit through the A cord is completed through the back contacts and'armature's of relay 30. The circuit from battery 29 througl the relayle at the B position is thus reestablished'to keep this relay energized; the

relay 14 being so designed as to operate on the superimposed signaling or'battery curproper party key at vthe A position. For

arranged through interrupting devices substantially the same as those shown at the A position to supply the proper 'current'combination to operate the signal of the called party and selected by the operation of the the relay R this circuit extends from grounded alternating current generator 70 or battery 71, having a positive side in termittently extended to .conductor72 by the interrupting device 73, thence through the front contact and right-hand armature of relay R, conductor 74, left-hand winding of relay 19, conductor 7 5, front contact and inner upper armature of relay 15, tip side'9'0 of B cord, and signaling relays 76, T7, T8 and 79 in parallel to conductor 80, thence to ring connections of jack 5and-plug (3,

inner lower armature and front contact. of

relay 15, conductor 81, right-hand winding of relay 19, eonductor 82','right-hand arma j ture'and back contact of'relay R left hand armature and back contact of relay R and conductor 83,jto ground. The; signaling relays 76 and 77 are biased so as to operate only on positive superimposedcurrent, and relays 78 and 7 9 onl on negative super-.- iinposed current, so tiat relays 76 and 77 would be the only ones operated by'the posif tive superimposed current in the presentinstance. These last mentioned relays closecircuits for their respective biased signals S and S but signal S is the only oneof the two to respond to the positive super imposed current supplied atthis time, the-1'10 circuit therefor extending from ground, .alternating current generator 70, over the cira cuit just traced tothe winding of relay 76,

thence by conductor 84 and armature and front contact of relay 76 to grounded signal r S; Relay 76 is thus locked up during the interval that superimposed signaling current is being supplied through-the interrupting device 73. When the interrupting device 73 connects direct current battery 71 to the conductor 72, the circuit through the relays of the signals is opened as the direct current will not pass the respective condeners present in the parallel circuit through the re- 1 On superimposed s gnaling currentagain being supplied, the

lays 76, 77, 78and79.

signaling circuit is again completed and the relay 7 6 again responds to complete the circuit to operate signal S, which is again actuated during the ringing interval. 7' i '130' i This intermittent operation continues untilthe subscriber thereat responds to the op-j eration of signal Sifby removing his'receiyer not pull up on 'alte rnating current but will either on director on superimposed current,

of the direct current circuit completed on shunting out of relay 76 withits condenser.

' The relay 19 after pulling upFWill hold up, however, on superimposedfsignaling current; The relay 19 is made slow to operate to prevent any momentary surge of direct current operating it prematurely, but the interrupt- 111g device 7 3 supplies direct current from the battery '71 a sufiicient length of time to enable it to pullup at this time. The operation of relay 19 removes the shunt path Y around relay 17, which is then energized.

Over a circuit extending from grounded bat- ,tery, front contact and left-hand armature h; of relay 8, conductor 16', Winding'jof relay 1,5, and lower Winding'of relay 17 to ground.

* The relay 15 is shunted out by the operation,

ofrelay 17 and disconnects signaling current from the B cord.

The lower armature of pulling up; the circuit through the relays Rf and 88,1 I H v p .tor on receuzlng ajlike indicati n from; the

which are in parallel, is momentarily opened.

' The-armature of relay 19 being pulled up' at" this time, thereby permits the relays 'R and 88130 return to normal position. The falling off of relay'R opens a circuit through relay complete a holding circuit extending from front contact andouter lower armature of relay 17,"and lower Winding of relayi'fl to connection is again established at thel'au mature and back contact of relay 19.

" Relay'17 inpull-ing up-Completesthe usual talking circuit through the calling'end of th e ture'and front contact of relay 98, conductor also provided aboutboth Windings o'f the relay 14:, this circuit beginning atconductor' 33 and extending over 'coriductor 91, front 1 contact and-inner lower 'armature;o f relay use. f v 1 .Sh d e slenal 2 w 17', conductor 94; and'condenser to s r so that'it' would operate on thecompletion 19, butthis'relay is made slow to release 1n order to give relay '17 time to pull 111p and,

grounded battery, front [contact and left- 1 hand" armature of relay. 8, conductor 16,

the appea e the A p tit on B cord and operates a relay-98 therein, which 'shunts'out" the left-hand Windingofrelay 14:,this shunt b'eginningat conductor 53: and I extending over conductors 91" and 92, arma-L '93 to the 'junctionofthetwo windingslof re- 1 lay 14: and through the right-hand windings, thereofto Winding 3d ofthe repeating coil;

A shunt circuitj for the alternating telephone I c currentsincident to speech transmissionis ii 'n f a s ataatisaagare let, to the' winding 34 of the repeating coil -fOn thelefthand winding of relay: 141

Ling shuntedout o f-the;;direct c en re a through j-battery' '29, f relay 36 at the fAgposi;

tion' operated to s pply battery es, ;t o,1 eep relay 23 energized', but ,providinggal.low re- 1 sistance path through the, armaturejand front contact of relay' 36 to; ground'to shunt out the jsupervi'sorysignal 27; j Signer 271Willthus be extinguished and thereby indicate to the A operator'thatthe callingpartyhas re-fl spbnded; H i I Conversation can now takeplaceoyer th usual talking circuitf-in whichfthe f ALop v eratorslcord provides a link circuit between; the line o f thejcalling subscriber and the trunk to the-B operator, andi on tem le; tion, the parties Will hang up their receivers l in the usual'fmann er. Thecircuit through;

the relay 981is thereby opened and the shunt} about the left-hand winding offrelay' 14 move v w er upon the e tan ld I thereof is again jincluded cthef arena; of ,the A cord through'the relayf36,'i'which' so margined as to fallloff underlthese png1r tions. [The shunt circuit about'ith'e lamp 3 .is thusremoved and th lam 2'?" again lightsc 1" up brightlyto indicate that' the called party has completed conversation. .,The"A]-'opera supervisory signal jf (not' shown) ja'ssoc'jiate'd with? the j answering end of her cord, fyvill lmow that disconnection is desijr'ed andla cordinglygpull out the plugs;oii' her co rd This breaks the circuit rough the' relays:

he y' T ese e ay fa e .it e i lay 23 on so doing opens thecircuit relay; 52, which h fa11$ i Ina mu h aS'relay'S was deenergized onth'e ireleasefo'i normal condition ready for. sub

' When the A operator disengagss,

at the Bposition is opened, whereupon this from grounded battery, arn1atu're 'andback},

y 2 bond tpr. 1, right hand armature slgnal-lamp 10 to ground,

iront contact} and;

the lamp and; il'ldieatihg tothe fBtoperator; that c n e on. k e' i e t Th 919-); w

erator thereupon "pulls iip-"the 6 the jacks ofthe'called. line, openinggthe Qci'rcuit 'ofrela' 8 cut-ofirelay 7 *of'the' t lays mmaries I the holding circuit'pf relay which; thereej upon drops. back,i restoring the ap aratus party line; 7

rmi we 'iibnii a s b e n I s uentfea 1 t e :plu

unreasonably long interval after the A op: erator has signaled the called party, it would indicate that the latter had not responded, in which event the A operator would so;

inform the calling subscriber and. withdraw the plug 20 from the ad: 21. The relay 14 would be deenergized thereby andcom'plete a circuit from grounded battery, armature and back contact of relay 14, conductor13,

inner armature and back contact of relay 7 12, conductor. 96, outer left-hand armature monic signals, the substation of the calling subscriberis represented at 103. The sub 'scribers liner terminates in a jack 104,

' position, and'on receipt of thecalling suband front contact of relay 88, conductor 97,

and upper winding of relay 17 to ground.

The relay 17 will. thereupon pull up! and shunt out relay 15, and also complete the holding. circuit, previously described, through the lower winding of relay 17. The relay 15, falling ofl', would openthe signaling circuit, while deenergization of relay 14 would light the signal lamp 10 to indicate disconnection was desired. The B1 operator would then withdraw the plug 6, opening'the circuit of relay Sand of cut off relay 7, andqrelay 8 falling 01f opens a holding circuit through the lower winding of relay 17 and also the circuit of relays R and 88, at the left-hand armature of relay 8. drop off, restoring the apparatus to normal condition. i

In Fig. 2, diagrammatically illustrating an embodiment of the invention as applied to a party line trunk system having harlocated at an answering or A operators scribers signal (not shown) .an A operator at that exchange would insert the answer ing plug 105 of an idle cord circuit into the I jack 104 and connect her operators set (notshown) with the subscriber in the usual manner. Onreceipt of. a party number on another exchange, theA operator gives only the line indication of the called party to the B operator at the desired exchange. Tl1e B operator tests the called line and on finding it idle'will insert the calling en'd 106.

'jack 107 completes aecircuitithrough the usual cut-ofi' relay 109 of the called line and also through a relay 110, controlling the circuit of a guard and disconnect signal lamp 111 at the '13 position. This circuit extends from. ground, winding of relay109, sleeye connections of ack 107 and plug 106, Wind Relays 17, R and '88 thereuponing of relay 110 to grounded battery. The" relay 110 pulling up closes a circuit to light the signal 111; this circuit extending from.

ground, signal'lll, right-hand armature and front'contact of relay 110, conductor 113, back contact and. inner armature of relay 11 4, conductor115, and backcontact and rent from the B position,this'circuitex tending from grounded battery, front vcontact and left-hand armature of relay 110, conductor 118,"winding of relay 117, conductor 119, lower armature and back contact of relay 120, conductor121 and back contact and armature of relay 122 to ground. A path also extends from the 'cond-uctor 119, through the lower windingof relay 120, to' ground, but relay 120 does not operate at this time, due to the low resistance of the path to ground through the armature and back contact of relay122 i.

' The A operator on receivingthe trunk assignment from the B operator will connect' the calling plug 123 of hercord circuit with the jack 124 of the assigned trunk Relay 7 125 at the A position is thereby operated over a circuit extending from grounded bat tery, winding of relay 125, conductor 126, sleeve connections of plug 123 and jack 124, and resistance 127 to ground. The opera tion of relay 125 lights a supervisory lamp. 195, associated with the calling end of the A cord; this circuit extending from ground ed battery, the right-hand armature and front contactof relay 125, conductor 197, lamp 195, conductor 198, back contact and armature of relay 128 to ground. The relay 128 is so marginedthat itwill not pull up in series with both windings of relay 116,

but will operate on the shuntingout of the lower winding of the latter relay, for aypun pose hereinafter described. e I

1 Another circuit is also completed on the connection of the plug 123 and jack 124 to operate the relay 116 at the B position, this circuit extending from grounded battery,

left-hand winding of relay 128, conductors.

129 and 130, back contact and armature of relay 131, ring connections of plug 123 and jack 124, conductor 132, winding 133 of repeating coil at the 13 position, conductor 134, both windings'of relay- 116, conductor .135, winding 136 of the repeating coil, conv-ductor 137, t1p connections of the jack 124 and plug 123, conductor 138, armature and back contact of relay 131, conductor 139 and right-hand Winding of relay 128, te-ground. The operation ofrelay 116 breaks the air I cuit of signal lamp 11at the B position, ex:

tinguishing it and indicating-to the crater that connection has-been'inade to the assigned trunk, The relay 128 did not op-' Bop- ' shown) are associated with keys 1 6 and C 1n the same manner andhave frequencies of relay 144, to groundfi The-relay 144 "ismade slow to operate so'that'hmornentary surges or current will not "effect its opera'-' crate at thistime and; accordingly the signal 195 will remain energized until the. called party responds, effecting. the; shunting out of lower winding of relayillfland Operation of relay a manner to be'later exp1ained. I w p p,

tion, andis also-so margined that itwil-lnot operate unless rthe relay 116 atthe 'B posi V tion' is shunted out from its operating "cire 20 1 a a I cuit. The A operator wouldnow operate one or the party line callin gkeysC,C ,C or C associated with theA cord used, correspondto the particular party called. 'The keys C, C C and C control the'intermittent application of alternating signaling current.

ing

and direct current, the alternating current generator respectivelyassociated with each key providing: current or .a particularfre-'- quency, depending on the particular party on the liner-each station on a party: line having a distinct frequency. T-n'the pres ent case'the generatoro145, associated with} key@C",' has a frequency'of 16?; cyclesper;

second, while similar generators (not respectively 0533-},50- and 66% cycles per second: A continuously rotating" interrupt I ingzdevice 146, provided for" each of the generators has two segments insulated from each other, one 1, segment .being "connected with :the generator145 and. the other; with a source of-direct current 147 so that alter- I tion, although obviously other 5 frequent} g'enerators.and signals could he used atathefl nating vcurrent and direct current will be alternately supplied to the:conductor"148.

I Assume, that the: key G, corresponding to I vice 146, conductor-148, outerandwmiddler upper spring or key C -,-conductor-149, winding of relay 144, conductor 150;front" the called party, has been operated and that relay-131haspulled uppers-previously e1;- iplained; Underthese conditionsalternating signaling currentzrrom the generator 145 and direct current. from the battery 147 are'g alternately connected-to the coiiductor 1:48; thew signaling circuit 7 extending; from grounded generator- 145,, 1 interrupting:- de-:

contact and upper, armature of relay 131-,

conductor 138, tip connections 0f,plug 123 and jack 124,;conducto'rs 137-and- 1 51,,con denser/152, winding-of harmonic relay-11', conductors 153 ,and175, inner lower garma- I i tureii and front contact of relay 117, conduc- :torsl5 4 and 1132, ring connections of jack rent of a frequency allotted to' key' C,'j-in r The operation 124 and plug123, lower arinatureandrront contact-or relayv 13 1, conductor .155,-middle tuned to" respond only to alternating curf the present case 16% cycles per second, while I relays H H and H are tunedfto'respond only tojlthe I frequencies iallottejd to their Irespective-keys C 'G 1 an d' 0*. I Currentniay, therefore, pass ini' arallel'.through'the wind-- 5 ings ofall ofthe harmonicrelays,"hntiorily i the one tun'edto" the particular'freque cy Wlll be operated. Thel relay116'is inade'so as to hold up over either superimposed usediin'the systempor on direct current and? is,' -therefore, energized at this timelfover Y 'a circuit from. conductor 137, through wind-" 1 6f ay" mpla e 5 energizing circuit fora; relay G associated} therewith, this. ;'circu t extending fronr gfound'ed batteryvi m Contact-and leftlf hand armatureof relay 110," conductors 15'(- and 158, arnoature andfl'ront contact of relay; H conductor ;159,twin'ding of relay) G,'con-i armature of relay 1222to ground;q;;Sin'1ilar-' relays G G ;qand G are "associated-fire;

spectivelywith the; relays l- I d, 11 1v I and when operated serve to close a circuit rrequencies'indicatjed on thedrawing gbein' the same as: those employed at the-A pos B position", i as could also direct'J-or" superimposed current signaling generators; appropriate; party signals to :coop'erate :ther w-1thwif deSiredJ- v f f f In the present case, operationof relay completesa holding circuit,lextending rrom 'j T grounded battery,'nfront conta'c't fand ileft f; Ii "hand 'arrnatureiofrelayi.ll(), g ndyi t fs 1 57;. r

andg1'62; winding ofvrelay; 114, conductor 163, leftrhand armature, rrent tome?- and 5 a winding of relay G's, condi'ictors' ltlQ and I :1, 'lay 122 to'ground, anfd'also results' in the uoperation' lor relay-1 1.4. *An alternatingl I generator having a E certainufrequency "de-r 1 pending onathe particular partysignalwith which V it I cooperates is; associated rsrespe 'tively witheachof relay- Gig Gr ,"G and as is also aniinterruptingfadevieeiinzgth 161 ,and back; contact and armaturei signalingcurrent-of any of the 'fre'que'ncies" 1 ductorsxl60fand 161 and back} contact and I 7100 to supply signaling current having thej' I 164 is furnished at regular intervals through a .circuit'extending from groundedgenerator 164, interrupting device 165, conductor 167, front contact and right-hand armature of relay G, conductor 168, winding of relay 122, conductor 169, front contact and upper armature of relay 117, tip connections of plug 106 and jack 107, conductor 170, thence in parallel through. the condensers 171 and windings of-the signals B, 13?, B and B at the different substations in the party line, to conductor 172, through ring Connections of jack 107 and plug 106, outer lower armature and front contact of relay 117 to ground. The signals 13 ,13 and B are not operated, however, as the harmonic signal B is the only one tuned to respond to the particular frequency of, the generator 164, associated with relay G. No direct current circuit is completed from battery 166 at this time, due to the condensers 171- in the circuit just traced, whilethe relay 122 is not operative on alternating current.

The operation of relay 114 results in the preparation for a circuit through its inner armature and front contact for a relay 17 3, thelatter circuit being opened, however, at the armature and back contact of the relay 116. until the latter falls off on short-circuiting thereof through the engagement of the outerarmature vof relay 114 with its front contact; this short circuit extending from conductor 137, by conductor 151, front contact and outer armatureof relay 114,

conductors 174. and 175,inner lower arma ture and front contact of relay 117, and onductor 154 to conductor 132. On relay 116 falling off, relay 173 operates, the circuit therefor extending from grounded battery,

armature and back contact of relay 116, conductor 115, inner armature and front contact of relay 114, conductor 176, winding of relay 17 3. conductors 180 and 161 and back contact and armatureof relay 122 to ground. Relay 173 operating, short-circuits relay114 by a path beginning at conductor $162 and extending over conductors 158 and 177, inner left-hand armature and front 7 7 contact Ofrelay 173 and conductor178 to conductor 163. .A holding circuit is also provided, extending from grounded battery, front contact and left-hand armature of relay 1-10, conductors 157, 158 and 177, in? ner left-hand armature,.right-hand armature, front contact and winding of relay 17 3,

conductors 180 and 161, and back contact and armature of relay 122, to ground.

The short-circuiting. of relay .116 'permitted the marginal relay 144 at the A posiductor 140, winding of relay 131, conductor;

141, and winding of relay 142 to ground. The engagement of the armature of relay 142 with its front contact provides a holding circuit therefor from grounded battery,

armature and front contact of relay 125,

conductor 181, front contact, armature and winding of relay 142, to ground, and shunts out. relay 131, which thereupon falls on. This opens the signaling circuit and thereby deenergizes relay 144.

In the meantime, on relay 144 being deenergized at the B position, the relay 116 is operated over the circuit previously traced through relay 128, this circuithaving been reestablished on deenergization of relay 131 and the removal of the shunt circuit about relay 116 on the retraction of the armature of relay 114.. I I

Intermittent signaling current will be automatically supplied to the called line and intermittently operate the signal of the desired party until he responds or the A operator abandons the call. Assume that the party calledresponds and'removes his re-' ceiver in the usual manner. The winding of signal'Bf is thereby shunted out by the V relatively low resistance path through the subscribers set extending from conductors 170 through the transmitter, switchhook and primary o f the induction coil 182, to conductor 172.- This path also permits passage of direct current from the battery 166 should circuit extendin from grounded battery,

front contact and left-hand armature of re lay 110, conductor 118, winding of relay 117, conductor 119, winding of relay 120, to

ground. Relay thereupon pulls up, I

completing a holding circuit from grounded battery, front'contact and left-hand armature of relay 110, conductor 183, front contact, lower armature and lower winding of relay 120, to ground. Relay 117 is thereby shunted out and allows its armatures to drop back, breaking the signaling circuit through the relay 122. Relay 120 in operating opens the circuit of relays G and 173 which accordingly release. Relay 122 pletion of the holding circuit for relay 120 and the release of relays G and 173 before is made slow to release to insure the comg 1041, thus restoring the apparatus at the relay 122. V: 1

A talking circuit, through the calling end of the B trunk is established by thelenergizas: tion of relay 120 and the falling; offTof-relay 117 this circuit extending-from battery 184,

V winding 185 ofrep'eating-vcoil', :conductorf 186, front contact andhupper armature ofrelay120, conductor 187;,backcontact and upper armature of -.re lay.. 117,= tip2i-connec+ tions of plug: 106 andjack 107, conductor.-

170, transmitter, 'hOokQsWitch-and primary v of the induction coil 1821at the 'calledsta "tion, conductor 172, ring-connections ofplug :tion, she would" withdraw plug 123* in the 106 and jack 107,,conductor 188;, outer lower" armature and backcontact'of relay 117, con-1: I ductor 189, winding of relay 190, and wind? ing 191 of the repeatingcoil to the other 7 184. The operation 'or'res lay 190 shunts out the lower winding of relay 116, which is of relatively highresistextending from grounded battery, armature side of battery" ance,"this shunt extending from conductor 134, 'over'conductor 192;: iront contact-and armature of relay 1'90 and conductor 193' to the junction of the upper'and lower windings ofrelay116.- f

The relay 128 contro -195 i at the calling end= o the A operatorfs cord circuit and the -shunting out -oftheg lower winding" ofrelay "116, permitting; the. relay 128 to pull 1ip-, -op'ening thecircuit previously traced for the .signa'l 195 at the armature and-back contact of-ielay 12 8.-

' erat'orfdisengagestheplug 106 from thejack hereupon relay *110 falls off, opening -Signal'1-95' is thereby extinguished, indicatthe A operator that the called party ing to has responded. The relay'1 16remainsenen gized on currentthroughthe upper winding and conversation t akes place between the subscribers in theusualnianner, the A operators cord serving as a link circuit be- I tween the calling subscriber and thetrunk circuit. On completion, the subscribers hang up their receivers and the circuit through the relay 190 is opened at the called station and thereupon falls back, removing the shunt about the lower winding of rey thereupon falls back, completing the fcircuit of signal 195, which, lighting up, in-

dicates that disconnection is desired. The

A operator would thereupon remove the I plug 123'from the jack 12%,openingthe circuit of relay 125', which on releasing breaks the holding circuit of relay'142, which then returns to normal position. Similar signals .(not shown) will be displayed at the answering end ofthe cord, and the Aoperator will remove the plug 105 from the jack position to normal. j

Relay116 at theB "position falls oii on ls a supervisorysignal 1'16. ltelay 128 will not hold up inv circuit with both windings of relay 116 and 1 istics,

I of said signaling, currents at light up signal lamp disconnectedfromthetrunk. The Bopefr aton then disengages plug 106 from the jack 107 breakmg the circuitof relayfllO and oiiFcut ofi relay f109 Relay 110, releasing,

opens a circuit to fextinguish lamp 111',- and,

also-opens the holding: circuit ofjrelay; 120,

which, falling-back, restores "the .apparatusa I of the B position to 2 normal condition-ready for'subsequ'ent use.

-Should the IA operator the called: party is still being .-signaled by 5 current from the apparatus or the B. p0s1 4 usual manner, whereupon the apparatus at n the 'A position would be restored to normal, aspreviously' outlined; Theflrelay116 ioffB positionwould droprioff and lightthe disconnect signal 111, as before explained, and also completeanener'gizingcircuit for relay 120,

and back contact orrelay 116, conductor',

winding-and inneriarmature andback contact 'of relay 114, conductor 195,. outer left-hand armature. 5 andQ-fron-t; contact of relay 17 3,1 conductor; I a s 196,}and u-ppen. winding or relay ftojf ground. "Relay-120 thereupon pulls upf, coin'-'}? f i ple'tingi-ajholding' circuit through its-lower? shunting: out relay- 117', which'a95 v I fallsj oif, opemngi the signaling circuitw The cir'cuit extending in parallel; through relays GQan d 17 3% is maintained until the-1B op-fl v, 10o the circuit through relays G' and 173,w-hich.-

thereupon return to{ normal" position: and

alsoopen the circuit ofthe signal111,;there 1. r

by extinguishing the latter-an'd restoring-the apparatus-of the VB position to normal conline also falls 01? on disengagement with the What is' claimed is and secondcentral'oflice, means at said first office to supplya plurality of signaling curr.- rents of different characteristics, V

to supply a plurality of signaling currents of difierent character;

' a link circuit at said first office adapted to, connect withsaid trunk'circuit, means means at, said second "oiiice at saidfirst ofice to connect-any'desired one said-first oiIice with said link clr'cuit, means associated with said. trunk circuit and operated by; the particular signaling current link circuit toautomatically connect a par connected to jsaidl 110 I 1. A telephone exchangesystem compris-j" ing' a trunkcircuit extending between a first ticular current from said current supply means at said second office 'wlth said trunk,

circuit, and means to disconnect signaling 05 'dition, The cut-off relay 109 of thecalled current at said first ofiice from said link circuit on signaling current' at said second oflice being supplied to said trunk circuit.

-2. -A telephone exchange system comprising a trunk circuit extending between afirst v and a second central ofiice, a source of signaling current at said first ofliceadapted to providea plurality of currents of different characteristics, a link circuit at said first oifice adapted to connect with said trunk circuit, a source of signaling current 'atQsaid second ofiice adapted to providea plurality of currents of different characteristics, means to connectany desired one of said currents 'at said first oflice with said link circuit,

means, associated with said trunk circuit and responsive to signaling current at said first ofliceconnected with said link circuit to connect a particular current at said second oflice, With said trunk circuit, and means operated on connection of a PELItlCllltLI'yCUII'QIIt at said second office with said trunk circuit to automatically disconnect signaling current at said first ofiice from said link circuit. 31 A, telephone exchange system comprisingqa trunkcircuit extending between avfirst and a second central office, a source of sigjcurrjentsuat said first office to said-link cirnaling. current at said first oflice adapted to proVi-dea plurality of currents of {different characteristics, a 'link circuit at said first voflic'endapted to connect with said trunk circuit, a source of signaling current at said second ofiice adapted to provide a plurality of currents of different characteristics, means to selectv and connect any desired onev of said cuit, ineans associated with said trunk circuit and responsive to signaling current at said first ofiice; connected with said link circuit to connect a particular current at said moomsi second ofiice with said trunk circuit, and means operated-on connection of a partlcular current at said second office with said trunk V circuit to automatically disconnect the signaling. current selected at said first oflice from said link circuit.

4. telephone exchange system comprising. a trunk circuit extending between a first and a second central oflice, a plurality of sources. ofwsignaling currents at said first trunk circuit to'connect a particular one of said currents at saidsecond ofiice with said trun'kcircuit, the particular circuit connected depending. upon the-particular current at saidfirst ofice connected with saidlink circuit, a calledsubscribers line adapted to be; associated with said trunk circuit, signals associated with said line andeach'responsive w di erent i one of said signaling currents at said second ofiice,-me an. to disconne t s g- T naling current. at said second office from; said trunk circuit on the cal-led subscriber responding, a d meansto d sconnect sign li g current. atsaid, second, ofiice from, s id: tr n circuit on-disconnection of said trunk and link circuits: prior to. re ponse; by s id. ca d subscriber;

In witness whereof I hereunto subscribe my name thistthfday of. August A. D. 1917.

' ell-mates W-KECKLERJ 

